Ferocactus wislizeni barely extends into Mexico, where two allopatric species, F. tiburonensis (G. E. Lindsay) Backeberg and F. herrerae J. G. Ortega, often are cited as varieties of F. wislizeni. All reports of intermediates with F. herrerae are based on normal F. herrerae, the subtropical species (R. S. Felger 2000).

The finely reticulate seed coat of Ferocactus wislizeni is diagnostic among the species of Ferocactus in the flora.

Benson 1982, FNA 2003

Common Name: candy barrelcactus Duration: Perennial Protected Status: No status in Arizona. General: Barrel cactus that is about as tall as wide, clearly a columnar plant with 20-28 ribs that are not markedly tuberculate. Spines: Hooked central spines obscure the stem, while the central spines are red but have a surface layer that is ashy gray with 4 per areole and forming cross, not flattened against the stem, these are strongly cross ribbed and 3-8 cm long. The radial spines are ashy gray with mostly 12-20 per areole, spreading and curling irregularly back and forth, but not cross ribbed. Flowers: Flower 4.5-6 cm diameter and 5-7.5 cm long, they can be orange, yellow or reddish and cup shaped with perianth parts which are narrowly lanceolate and apically sharply acute and mucronate while being borne on the crowns of the stem with a distinct purplish middle stripe. Fruits: Yellow and barrel shaped, they are fleshy and covered by numerous almost circular but shallowly fimbriate scales that are readily dehiscent through basal pore. Ecology: Found on deep soils of igneous and limestone origin, sandy desert soils, gravelly slopes, wash margins, alluvial fans, lower edges of oak woodlands and grasslands from 1,000-4,500 ft (305-1372 m), flowers July-September. Notes: The primary species of barrel cactus in the region, distinguished by being to 1 m tall, the flattened, hooked spines and showy yellow fruits at the apex. Called the compass cactus because it tends to lean south toward sun, species can live up to 100 years. Spines are said to cripple a horse unless they are treated the same day. Ethnobotany: The top of the cactus was lopped off and the interior pulp was crushed as a source of water in extreme circumstances; the seeds were parched, ground, and boiled into a mush; the spines were used as fish hooks by the Pima, and the fruit was made into a candy. Etymology: Ferocactus from Latin ferus, fierce and cactus referring to spines, while wislizeni is named after Frederick Adolf Wislizenus (1810-1889) an Army surgeon, explorer, and botanist. Synonyms: Echinocactus wislizeni Editor: SBuckley 2010, FSCoburn 2015